Die boards are generally used to cut and/or crease one or more layers of sheet-type work material, such as cardboard, for use in the manufacture of various different articles. One such use, given here by way of example and not to be construed as limiting the present invention, is the fabrication of box and package blanks which after having been cut and creased by the die board, can be folded into finished boxes or product packages.
Usually, the die board consists of a base made from a thick piece of material such as plywood, that has a series of slots cut into it. These slots are arranged in a pattern corresponding, for example, to the outer periphery of a box or package blank, and the lines along which the blank must be folded to create the finished box or package. Rules, which generally consist of pieces of steel cut to lengths and/or bent to correspond to the slot length and configurations in the base, are then inserted into and protrude from the slots. The amount by which a particular rule extends from the slot depends on whether the rule will be employed to cut or crease the sheet material. Generally, during a cutting and creasing operation, the sheet material is positioned under the die board and pressure is applied to the board via a press, causing the rules to engage the sheet material, thereby cutting and creasing the sheet material.
In known methods of fabricating die boards, difficulties are often associated with the formation of the slots that must be cut into the die board base to accommodate the rules. Typically these slots are cut into the base in one of two ways; (1) using lasers, or (2) using a jig or band saw. The capital cost of a laser is generally very high, in addition, the use of lasers tends to be expensive and complex. Large amounts of power is required to operate the laser, and the beam must typically be shielded using an inert gas. Another difficulty associated with using lasers is that the slots produced tend to have scalloped edges. When the rules are inserted into these slots, rather than having line contact between the slot edges and the rules; the rules engage the slot edges at discreet points corresponding to the "peaks" of the scalloped edge. This reduces the stability of the rule in the die-board, increasing the potential for inaccurate cutting and creasing when the die board is used. This problem is further exacerbated due to the fact that the heat associated with the laser tends to dry out the board resulting in dimensional distortion of the slots being cut and warping of the board. A further problem also attributable to the heat of the laser is that smoke is generated from the material being cut. The smoke causes environmental problems which must be addressed, resulting in further increases in operating expense.
When a jig or band saw is employed, a starting hole must be drilled at one end of the slot to facilitate insertion of the blade associated with the saw. This requires an additional operation, thereby adding to the cost associated with fabricating the die board. Furthermore, these slots are often cut by hand with the inaccuracies resulting from human error making it difficult to insert the die board rules into the slots. The potential human error can also result in inaccurate die cutting. In addition, when using a manual process, the cut lines must be transferred by hand onto the die board.
Based on the foregoing, it is the general object of the present invention to provide a die board and a method for manufacturing the die board that overcomes the difficulties and drawbacks associated with prior art die boards and their manufacture.
It is a more specific object of the present invention to provide a die board fabricated using rotary cutting tools that is not subject to the above-described inaccuracies.